Related Experiment Videos
Analysis of oncogenes, tumor suppressor genes, autocrine growth-factor production, and differentiation state of human
R J Isfort1, D B Cody, G Lovell
1Corporate Professional & Regulatory Services Division/Human Safety Department, Procter & Gamble Company, Miami Valley Laboratories, Cincinnati, OH 45239-8707, USA.
Abstract:
Human osteosarcoma and fibrosarcoma cell lines were investigated for alterations in oncogenes, tumor suppressor genes, and growth factors, all of which have been implicated in tumor formation. Characterization of oncogenes that are involved in osteosarcoma formation, including the c-fos and c-myc oncogenes, indicated that all six osteosarcoma cell lines examined had 5- to 20-fold amplification of the c-myc oncogene, whereas neither of two fibrosarcoma cell lines c-myc amplification. Interestingly, only three of six osteosarcoma cell lines displayed altered c-myc immediate-early gene function. c-fos was found to be normal, both at the gene and functional levels, in all six osteosarcoma and both fibrosarcoma cell lines tested. Characterization of two tumor suppressor genes, p53 and RB1, that have been implicated in osteosarcoma formation indicated that p53 was altered in five of six osteosarcoma cell lines, whereas RB1 was altered in only two or six of these cell lines. Neither RB1 nor p53 was found to be altered in the fibrosarcoma cell lines tested. An additional transformation marker, autocrine growth-factor production, was observed in all six osteosarcoma cell lines and both fibrosarcoma cell lines examined. Finally, the differentiation state of the osteosarcoma cell lines was investigated via the bone differentiation markers alkaline phosphates and osteocalcin. Alkaline phosphatase activity was observed in four of six osteosarcoma cell lines but not in the two fibrosarcoma cell lines examined. The alkaline phosphatase activity was a result of the expression of the bone/liver/kidney alkaline phosphatase isoform. High-level osteocalcin expression was observed in one of the osteosarcoma cell lines but not in the two fibrosarcoma cell lines examined, although all cell lines demonstrated low-level osteocalcin expression. Together, these data demonstrate that relatively undifferentiated osteosarcomas commonly display c-myc amplification, p53 and RB1 mutation, and autocrine growth-factor production, all of which may play a role in osteosarcomagenesis.
Insights
Human osteosarcoma cell lines frequently show c-myc oncogene amplification and p53/RB1 gene mutations. These genetic alterations, along with autocrine growth factor production, are implicated in osteosarcoma development.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Osteosarcoma and fibrosarcoma are bone cancers with complex genetic underpinnings.
- Oncogenes, tumor suppressor genes, and growth factors are critical in tumor formation and progression.
- Understanding genetic alterations in these cell lines aids in elucidating osteosarcomagenesis.
Purpose of the Study:
- To investigate alterations in oncogenes, tumor suppressor genes, and growth factors in human osteosarcoma and fibrosarcoma cell lines.
- To characterize the role of specific genes like c-myc, c-fos, p53, and RB1 in osteosarcoma development.
- To assess autocrine growth factor production and differentiation markers in these cell lines.
Main Methods:
- Analysis of gene amplification for c-myc and c-fos oncogenes.
- Assessment of gene alterations for tumor suppressor genes p53 and RB1.
- Detection of autocrine growth factor production and expression of bone differentiation markers (alkaline phosphatase, osteocalcin).
Main Results:
- All six osteosarcoma cell lines exhibited 5- to 20-fold amplification of the c-myc oncogene; fibrosarcoma lines did not.
- p53 alterations were found in five of six osteosarcoma lines, while RB1 alterations were present in two.
- Autocrine growth factor production was observed in all osteosarcoma and fibrosarcoma lines; differentiation markers showed varied expression.
Conclusions:
- Relatively undifferentiated osteosarcomas frequently display c-myc amplification and p53/RB1 mutations.
- Autocrine growth factor production is a common feature in these osteosarcoma cell lines.
- These genetic and functional alterations likely play a significant role in osteosarcoma formation.